http/2 and mail.de not working with DAVdroid 1.0.8

Hi,
after upgrading to 1.0.8, my connection to my mail.de calender/contacts were broken.
I removed all the app data and app itself and after a clean install, I tried to add a new account using email/password of my (mail.de account).
My problem looks quite similar to the one here.
But I can’t force mail.de to modify their installation to shut off http/2
This is what I get:

Since 3rd may, my mail.de accounts expired the same problem with DAVdroid.
After successfully connected to mail.de calendar with Evolution under Linux, i get in contact with mail.de support team.
They now deactivated HTTP/2 and the issue is solved temporary. Its no problem on mail.de side!